Telephone-exchange.



No. 694,9l8. Patented Mar. 4, 1902;

' u. u. HOLLAND.

TELEPHUNE EXGHANGE. (Application filed min; as. 1901.

(No Model.) 3 Sheets-Sheet L Inn/910607:

N0. 694,9l8. Patented Mar. 4, I902.-

N. H. HOLLAND.

TELEPHONE EXCHANGE.

(Application filed E91). 23, 1901.]

3 Sheets-Shegt 2.

- (No Mo'dei'.)

amt

if RU A \NQ a e g In. U DE l m ml R m a $1 MB] a WewrmwJiTJib W gees e5 I Patented Mar. 4, I902. N. H. HOLLAND.

TELEPHONE EXCHANGE.

(Application filed Feb; 23. 1901.)

3 Sheets-*Sheot 3.

(No Model.)

I 22660), M71115 E ttli /a esiges:

THE uaims UNITED STATES PATENT OFFICE.

NEWMAN H. HOLLAND, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TO CHARLES W. I-IOLTZER, OF BROOKLINE, MASSACHU- SETTS.

SPECIFICATION formingpart of Letters Patent No. 694,918;dated March 4, 1902.

' Application filed February 23, 1901. Serial No 48,5663 (N0 mfl eh) To all whom, it may concern:

Be it known that I, NEWMAN H. HOLLAND,-

which will indicate when a busy line is clear in case a subscriber has called for connection with said line while it was connected elsewhere, the signal also being provided with means for indicating not only the line called for, but the line which has called for it. Assuming, for example, that a certain subscriber wishes to be connected with a certain other subscriber whose line is found to be busy at the time and also expresses a desire to be connected with said busy line as soon as it is disengaged, the operator at the central office can connect the line called for with a signaling device which will not actually operate until the said line is disengaged, the device being also provided with means for indicating after the signal is displayed the line of the calling subscriber who asked for the connection.

The invention is applicable to any existing telephone system and may be operated through the agency of the ordinary cord connections in conjunction with a suitable table key or switch which will connect the circuit of the said signal into the line, so as to be properly operated, or through the agency of a special cord-circuit without the intervention of any switch. By utilizing cord-circuits in this way the plugs serve as indicators to show the line wishing connection and the line with which connection is desired,and,fu rthermore, both lines are in this way connected with the signaling device, so that if the calling-line while the subscriber is waiting for the line originally called for has obtained connection elsewhere the signal will not be displayed even when the called line is free. \Vhile not essential, this is an important feature of the invention, since the signalwill not be displayed until both lines are free, and the op erator has nothing to remember, as the plug indicates which line they are.

In a multiple switchboard each operator is provided at her own board with a certain number of answering-jacks, which represent the lines under her charge, and a complete set of calling-jacks, representing all the lines connected with the station, and the several calling-jacks of each line, which are distributed throughout the several operators boards, are connected together and provided with a common ground connection. The several ground connections are for the purpose of completing a local circuit at the central oftice for va-- rious purposes in accordance with the system in use, as will be hereinafter fully described, and these ground connections are utilized in the present invention to close a circuit through the special signaling device, which will remain closed so long as either of the lines which are waiting connection is in use. The special signaling-circuit is arranged to be connected either by the regular plugs or by special plugs with a ground connection of its own, the jacks of each of the lines which are awaiting connection thus being grounded through the special signaling circuit. these lines, therefore, is connected with some other line at any board, one terminal of the central-office battery is connected with the ground through the jack in which the plug belonging to that line is inserted, and as the other terminal of the centrahoffice battery is grounded it is obvious that a circuit will be completed through the, said signaling device until the said line is disconnected by the removal of the plug. The signaling device is preferably arranged in a closed circuit, in which case it is adapted to be displayed when the said closed circuit is broken, which will only occur when both of the connected lines are disengaged.

It is to be understood, of course, that the term ground is used as indicating a common return-circuit, which under the existing conditions is usually metallic, but is more conveniently illustrated as a ground, this term being commonly used for convenience with this significance and conventionally illustrated in the drawings. It should be further If either of understood that while this special signaling device may he more conveniently arranged in a closed circuit it is not necessarily so arranged, as an open circuit could be employed which would be closed on the removal of the plug from the jack of the line with which connection is desired.

Figure 1 is a diagram of these telephonestations operated on the local-battery system, showing the connections at the central office, so far as they relate to the present invention; Fig. 2, a similar diagram showing the invention embodied in the common-battery system; Figs. 3 and 4, details to be hereinafter referred to.

Referringto Fig. 1, which illustrates a practical device embodying the invention as applied to the system in which local magnetos are employed for signaling purposes and in which the ordinary cord-circuit is utilized in conjunction with a suitable table keyor switch to operate the special signal, it may be assumed that station 241 is connected with station 1409 and that station 411 has asked for connection with station241, for example, and has been informed that the said station 241 is connected with another station or busy, as is shown in the drawings. Under these circumstances the operator will place one of the plugs a of a cord-circuit in the'answeringjack 1) of station 411 and the other plug a? of the same cord-circuit in the calling-jack b of station 241, which is located at her own board, at the same time manipulating the table-key c, which forms partof the special signaling system embodying the present invention. The said table-key is so arranged as to open the circuit of the tip-wire a (normally closed through contact member 0 so that when the key is manipulated there is no outside connection between the two lines in the jacks of which the two plugs have been inserted, and the thimble-wire a by the same operation is connected through the switch member 0 with a wire 01, which passes through the special signaling-magnet h to the ground G. The thimble of the jack b of the busy line as 'well as the thimble of the jack 1) of the waiting line are therefore both connected with the ground, and as all the thimbles belonging, respectively, to said lines are connected togetherit follows that every thimble belonging to either line is grounded. WVhen the tablekey is in normal position, as when two lines are connected together for conversation, the

tip-wires a are connected through the switch member 0 and the thimble-wires 0. instead of being ground, are connected through the tery D and passing through conductor a, switch member 0 conductor 0. to the thimble of one of the jacks 19 from which it passes to the thimble of the jack b in which the other cord-circuit has been inserted, thence through the wire a switch member 0 wire a, electromagnet h to ground G and back to the battery. Said-electromagnet it therefore will be energized so long. as the line which is wanted remains busy, but will be denergized as soon as the active plug has been removed, no matter at what part of the multiple switchboard the said active plug has been inserted.

The electromagnet h, above referred to, is shown as having an armature 72, adapted to control a drop 7L which makes contact with the terminal of a special signaling-circuit 2O 22 through a local battery 21 and a lamp 23, the other terminal of said circuit being arranged to make contact with the armature 71, when the said armature is restored tonormal bythedenergizingofthemagneth. Ifthesaid magnet is denergized, a portion of the arn1a ture 71, will make contact with'said terminal, closing the circuit through the magnet-frame and lighting the lamp 23, which constitutes the said special signal. This will only happen when all the plugs which may have been connected with any of the jacks of station 241 are removed, because'as long as any plug is in any jack of said station at any board there will be a complete circuit energized by the battery D through the magnet h. Consequently so long as the station 241 is connected with any other station on the line the signal 23 will not be displayed, but as soon as the said station 241 is disconnected the said signal will be displayed and the operator at the central office will be informed that line 241 is free. Having previously inserted the plug a in the answering jack of line 411, which desires connection with station 241, the other plug of the same cord-circuit being already inserted in one of the calling-jacks of station 241, it is only necessary to release the table-key c and send a signaling impulse over the line, which will call the subscribers at stations 241 and 411, which stations are already connected by the cord-circuit.

In the diagram the several jacks, only three of which are shown as corresponding to each station, are apparently on the same board; but it is to be understood that there are a large number of the calling-jacks distributed throughout the central station, each operators board containing one only besides the answering-jack, and that the plug a, which is shown in jack b of station 241, may be at a board remote from that in which the cordcircuit containing the special signal is located, so that the operator at the said board has no means for knowing whether station 241 is connected with any other station or not, except through the special signal described. It may happen that the busy line called for is connected'at the operators own board, in which case the calling-jack at the said board is not available for the plug of the cord-circuit which is, to control the sigcated by the reference-letter A and having.

been described'in detail, and for convenience a batteryis shown in eachvone of the. said.

r not essential.

, any cord-circuitwhich may be at her com-V nal. In View of this fact it is wellto pro.

vide each operator with one special cord-circuit having a plug adapted to fit ov'erand make contact with the ordinary plug, as in dicated in Fig. 3, the said plug being india contact-piece A adapted: to make contact with the sleeve-wire terminal of the ordinary plugin order to obtain the ground connec tion to complete the circuit for the special signah i The co rd-circnitwhich connects station 241 with station 411 is shown as provided with the same signaling apparatus as that which has cord-circuits, each battery having a groundterminal. As a matter of fact a'common hat ter y would beused for all thefcord-circuits,

and. the. same battery may conveniently be employed for this purpose as is now employed for the busytest, although this is obviously In the construction hereinbefore described, however, each cord-circuit at any one operators board is provided with a special table-key and aspecial signal 23, and. when the operator is asked ifol? connection with a line which .provestoihebusy shelcona,

nects'the two lines inthe ordi nary way with Y Y mand, but operates the table-key belonging to the said cord-circuit which places the SPB";

cial .signalin circuitas described, sothat as soon as said signallis displayed sheis made aware of the fact that the two lines which the callingsubscriber has wished to have con}. nected are free to be connected andshe acts accordingly, restoring. the conditionsto nor mal'bythe manipulation of vthetable-keythat is, the restoring of the said table-key to its normal condition. 1

Inthe particular system thus far described the special signal23. is included inn local-battery circuit whichimust be closed only when the current ceases to flow through the,cord-.-

circuitwhich indicates the two stations which are waiting tobe connected together. lt is necessary, therefore, that 'the. said circuit should be normally. open and that when the signal is to be used it should be placed in conditionlto befinally closed,bnt thatit should not'beclosed until-the signal is 'to be displayed A simple expedient for accomplishing this result is herein shown, the armature 712 of the magnet h being arranged tosupportv a drop 72,3, whichffalls' into contact with one end of a special-battery circuit when the magnet h is energized, the said drop being held up by the armatn re ofsaid magnet when I in its normal position. l he lifting of the ar: mature, however, pulls the said armature out 1 of contact with the opposite end of said circuit, so that the circuit is still-open, oneend thereof, however, being connected withthe magnet-frame. by the drop which has been previously released. As soon .as the. magnet which connectsltwofllines in use and a cord;

circuit connecting the two.lines which are waiting. lt willbe seen, however, thatin any of such arrangements so long as a station with whichconnectionis desired is connectedat anyzpoint in the multipleswitchboard with any-other station. the said signal-circuit will be controlled by any plugin, any of thejacks belonging to the said station. and'that the sig: g jnal willnot be, displayed solong as the, said line isconn ected at. any point inthe central:

i In order, to juitherillustrhte,theadaptability of thelinvention to any existingsystem and also to illustrate a. modification in the arrangement of. the specialsignal at thecen-g;

tral ofice, theinventionis shown in.F i g., 2 as.

signal" is includedin a special cord-.circuitim .IOC applied. to the socalled-f central-energy]? 'or fcommon-batterysystem, and. the special stead of in. each. of .the .regularicorctcircnits'acombined with a. special controllingdeviceor.

tablekey, ashereinbefiore.described.v In the central-energy system all the-jacks belonging to the same lline are connected togetherand grounded-so as to receive current from, the battery at thecentral office wheneveracon;

necting cord-circuit is in. oneof v,thejacks,

the said battery thus notonlyserving toopcrate the busy; test, but also commonly serv;

ing to energize aspecial electromagnet when thelines are in. use in order. tocutontthe permanent signaling'battery which is 0111131113.

line all .the time, but openscircuited bythe condenser except when a signalis beingsent in. Referringto. Fig.2, in which thesanie reference-letters will be used, so 'far aspos-- sible, as those alreadynsed in Fig.1 to identify analogous parts, it maybeassuined that.

station 241 ;is connected with. station 14:09 through. the usual, cordecircuit having. the

plugs a and a? inserted in the, jacks b?..b e longing to the two stations, respect i s elyl 'ljhe. usual clearing-out signal or. ring-off .dropreir cuit is illustrated, butneed not. be described in detail; sinee it-forms, nopart ofithepres:

'ent invention. Itwill be seenfhowevenby tracing the circuits that so long as any plug a stands in anyjack b? of station Qel-one ter .v

ininal of the battery Dowill beconnected through conductors ,alfl: a, 03 13 5 and (0 with the thimble of the jack b of said station 241, which thimble has a permanent connection with the ground G. In the construction shown the special signal 23 is controlled by an electromagnet h, one terminal of which is permanently connected with the ground at G, the other terminal being connected with both wires of a special cord-circuit 6, having two plugs 6 which are adapted to be inserted, respectively, in the answering-jack b of the line which desires connection and any calling-jack b of the line which is found to be busy, in this case the line belonging to station 241. The said cord-circuit thus indicates to the operator at the central office the two lines which desire connection and so long as either of the said lines is busy, so that any of the thimbles belonging to the said line is connected with the battery-D, current will fiowfrom the batteryD over the circuit above traced, part going to ground over one member or the other of the said cord-circuit e and through the electromagnet h. In Fig. 2 only two jacks are shown as belonging to each station, and it may be assumed that the jacks shown as belonging to station 241 are both calling-jacks, the answering-jack being omitted. At station 411, however, the jack 1) is supposed to be the answering-jack belonging to said station and located at the board of the operator whohas received the call, as this is the jack in which she would place the special plug as an indicator, the other plug being placed in that one of the calling-jacks belonging to the station desired which is located at the same board. In reading the diagram, therefore, it should be assumed that the answering-jack b belonging to the station 411 and the calling-jack b in which plugs e are'inserted are located at the same board and that the jack b in which plug a is inserted is at another board, the said jacks being connected together, however, by the conductor a The signal 23 is shown as included in a circuit 20 to 22, having a local battery 21, the said circuit being adapted to be closed, as illustrated, when the armature of'the electromagneth is released, the said armature acting'upon a contactpiece 24. The current will continue to flow through the electromagnet 71. so long as any thimble belonging to either of thelines which are waiting to be connected has the plug of a cord-circuit connected therewith, and the signal 23 will not be displayed until both of the lines in question are clear. Upon the display of the signal the position of the plugs e of the special cord-circuit 6 indicates to the operator the two lines which desire connection, and the special cord-circuit can then be replaced'by one of the regular cord-circuits toconnect the two lines together. In order to prevent the display of the signal 23 when the cord-circuits are not in use, the electromagnet his adapted to be energized by a local battery II, one terminal of which is connected with each member of the special cord-circuit e and the other terminal of which is connected to a plate H upon which the metallic contacts c of the plugs 6 rest when the cord-circuit is not in use, thus completing the battery-circuit and maintaining the electromagnet energized. So long, therefore, as either of the pln gs e rests upon the plate H the signal 23 will not be displayed, and as soon as eitherplug is connected with the thimble of the busy line the electromagnet 72. will be placed in circuit with the battery D, so that the signal 23 will not be displayed at any time except when it has been placed in condition to indicate that a busy line in which connection is desired has become free. In the case of party-lines the cord-circuit which is utilized for the special signal (or every cord-circuit when table-keys are used) may be provided with an indicator 1, as shown in Fig. 4, which can be turned or otherwise manipulated after the plugs are in placein order to show which part-y on the line is awaiting connection.

In the foregoing description the systems which have been chosen to illustrate the invention have been described in detail in order that the invention may be clearly understood. It is obvious, however, that the specific construction shown is not essential to the invention, the problem being merely to provide the operator at the central office with a special signal which can be tapped onto a busy line, so as to be displayed when the said line is free, accompanied by any suitable means for indicating the line which has previously called for the busy line and wishes connection therewith as early as possible. It is essential only that the said signal should be controlled in such a manner as to be displayed only when there are no plugs in any of the jacks belonging to the line which has been found to be busy and that any kind of an indicator might be used to inform the operator which line is to be connected when the busy line becomes free. The use of the plug connected with the said circuit, however, as an indicator is not only a convenient way for indicating the calling-line, but possesses a further important advantage in that it places the calling-line also in connection with the special signaling-circuit, so that if the said calling-line after it has sent in the call and before the busy line has become free has been connected with another line at some other part of the board the signal will be controlled by the said calling-line and will not be displayed until both of the lines desiring connection are free. It is not, however, intended to limit the invention in this respect, since it is believed to be broadly new to provide the central-office system with a special signal adapted to be connected with a busy line and to be displayed when said busy line is free,

combined with any means for indicating to the operator at the central office the callingline which desires connection with the busy line at the earliest possible moment.

Whilc, as has been stated, the busy-test battery may conveniently be employed for the purpose of actuating the special signal,

the common busytest must not be confused with the opposite terminal of said battery;

with the invention, for the reason that, assuming, for example, that the operator at central were to keep memorandum of call,- ing-lines and the lines with which connection is desired, she could only ascertain if thebusy lines had become free byapplying the busy test from time to time, and connections might be and'probably would be made between times, so that the operator of the central oftice would be in exactly the same position in which a subscriber is placed who're: pcatedly calls for a given line and is unfortunate enough to call each time just after a connection has been made elsewhere. In accordance with the invention, on the other hand, as soon as the special circuit has been connected with the busy line and the indicator placed in position, these operations entailing substantially no additionalwork on the part of the operator, there is nothing more to be done, as the display of the signal will call the operators attention to the fact that-the lines wish connection and are both free, and the indicator and circuit connection impart the desired information as-to whichlines are to be connected. Furthermore, the signal embodying the invention should not be confused with the ring-oft dropor clearing-out signal, I

as this signal imparts no information except 7 at the'board where connection has been made,

. nected with one board the clearing-out signal affords no indication of the line which has been unable to get connection.

I claim I a 1. In atelephone system, electrically-connected hacks for each incoming line; cord conductors for connecting a jack of one line to a jack of another line to establish com munication; a signaling device; a controlling device for preventing the operation of said signaling device while two lines are connected for communication; a special circuit for said vnecting cord-conductor set and a-jack connected with the jack which has been connected withsaid special circuit.

2. The combination with the sets-of connccting cord conductors each of which has one of its conductors provided with a contactpiece connected with one terminal of a battery; of the jacks for theincominglines, each having a contact for connection with the said contact-piece, the several jacks for the same line being connected together electrically; a special signal; a controlling-circuit for said special signal, one'end of which is connected of the signal while two liuesarc connected.

1 In a telephone system, the combination with the several electrically-connected sets of jacks belonging respectively to the several lines; of the sets of cordconductors, each of which has one of its conductors connected with one terminal of a battery, said-conductor being'provided.with'a contact-piece to make contact with any jack; a special circuit. having a connection with the opposite -terminal of thebattery aforesaid and means-for connecting the said special circuit with any jack; and asignal controlled by said circuit,

said circuit being arranged to'prevent the operation of said signal while two lines are con-v nected-for communication.

. 4. In a telephone system thecombination with means forconnecting two lines for communication; of a special conductor adapted. to connect one contact of a jack of acallingline with one contact ofa jack of a busyline without coi'inectiug the other contacts of said jacks ;toestablish communication between said lines; a source of current one terminal.

of which-is connected with said busy-line-jack contact, the other terminal being connected with said special conductor; a special signal controlled by said source of current; and

means for preventing-theoperation of said sig-' nal consisting of a circuitcontrolled by the means for connecting two lines forcommunication. I -5. In a telephone system, aspccial signal; a circuit controlling said signal, one terminalotwhich is adapted tobe connected to one contact member of anyjack, the other termi- 'nal being connected with one terminal of a battery; electrically-connccted jacks-for each incoming line; conductors for connecting one line with another, one-member of-each sctof cord conductors being normally connected with the other-terminal of said battery; acoutaet-piece forsaid member adapted to make contact with that member of the jack ,which.

is connected with the bat-tery-terminalwhcreby the circuit for thespccial signal is-c'ontrolled; and means forindicating the linelto which said special signal refers.

6. In a telephone signaling system a spe-n cial signal for the purpose described; a'circuit for controlling said signal; sets 0t con- -d uctors, one conductor of each set-having one terminal adapted to be connected with one terminal of said circuit; jacks having coop.-

erating terminals; means for connectingsaid jack-terminals to the other tcrm-inal'of ."said circuit; and means for indicating the line awaiting connect-ion, as set tortln f I jacks; of sets of conductors cooperating with said jacks to connect two lines for purposes of communication; a special conductor adapted to connect one terminal of a jack of a calling-line with one terminal of a jack of a busy line; a special signal; and a circuit for said special signal controlled jointly by the c011- d uctors aforesaid, substantially as described.

9. In a telephone system, the combination 20 with central exchange apparatus; of a special signal; a cord-circuit for connecting two lines for communication; a special local circuit for controlling said special signal, one terminal of said circuit being connected with one member of said cord-circuit; means for connecting the other terminal of said circuit with a jack of a busy line, whereby a signal is displayed when the two connected lines are disconnected; and means for indicating the waiting line to which said signal relates.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

NEWMAN H. HOLLAND.

Witnesses:

HENRY J. LIVERMORE, J AS. J. MALoNEY. 

